I know that 2 and 3 are the pressure ontop and below the wastegate. If you want it to open at its most MINIMAL setting, then use the top one, because it is pushing against the spring and helping it to open. If you want it to stay shut as much as possible, then use the one below.
On my Soarer, we have the top wastegate (#3) hooked upto the boost control solenoid, then the other side of the boost control solenoid to the inlet manifold, so it opens at its lowest setting and doesnt overboost.
Hope that helps, im sure someone else will be able to tell you exactly what to do.
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